i use AWS cloud formation to create zend cluster instances. i use "userData" parameter to set ZEND_CLUSTER_PASSWORD, ZEND_CLUSTER_DB_HOST, ZEND_CLUSTER_DB_USER, ZEND_CLUSTER_DB_PASSWORD and it works very nice !
I use jenkins with AWS cloud formation and i want to set API KEY to deploy on the Zend Server. Is there a specific "userData" to set the API KEY like ZEND_CLUSTER_PASSWORD ?
I dont find any documentation for user data parameters and any help will be welcome.

It is not possible with our latest ami and template.
I will see if we want to add this option for next version.
Do you want change the ami and template yourself and do it? I can try to instruct you on doing it.

Custom Zend Server AMI is problematic. Startup script in Zend Server AMI are designed to run only once after boot and configure everything.
If you start Zend Server instance on AWS and then try to create AMI from it you will finish with AMI that won't do anything with user data at boot.
So creating custom Zend Server AMI is definitely not an option.
About outputting admin WebAPI key. The question is where do you want it to be output? We currently do save cluster WebAPI key in /var/tmp/zend_cluster.sh file. This file is later used by Zend Server to deregister from Zend Cluster when instance is shutting down. So if you do take it from there, please do not modify this file.

Thx for your response, i discovered a remedy : i release DB from a overview and then kept my settings.
Is it possible to use Meta-data residence in the json computer file to make environement varying ?